This invention relates to a three-ring binder having an actuating crank.
Many modem ring binder mechanisms have actuating levers for opening and closing two, three or more rings. In some such devices, the levers also lock the rings closed. The typical arrangement is to attach the bottoms of the ring halves to hinged plates confined between the edges of an arcuate metal housing which provides a toggling action as the plates snap between open and closed positions.
Other devices have been proposed in which the rings are opened and/or closed by a cam-type mechanism. Prior such constructions are seen in U.S. Pat. Nos. 778,910, 2,494,898, 2,789,561, and 2,894,513. U.S. Pat. No. 778,910 discloses a two-ring binder which is opened by lifting the end of a lever which depresses a crank whose ends are the movable ends of the two rings. It would be advantageous to have a three-ring mechanism of the crank-actuated type.
An object of the invention is to improve the operation of a crank-operated ring binder having three or more rings.
These and other objects are attained by a three-ring binder having a support plate, and at least three rings, each comprising a movable segment pivotally attached to the support plate and an immovable segment affixed to said support plate, and a mechanism for moving the rings between an open position and a closed and locked position. The mechanism includes a crank pivotally supported on the support plate for oscillation about a longitudinal axis. The crank has plural throws offset from the longitudinal axis. The movable ring segments are integrally attached to said crank. A leaf spring biases the crank toward a rings-closed position, and a manually operable lever moves the crank toward a rings-open position. The lever is pivotally mounted on said support plate and depresses the throw, moving the crank towards its rings-closed position, as the lever is depressed.